Recent Antarctic Sea Ice Extremes in the Historical Context of the 20th Century

Antarctic sea ice has been behaving in dramatic ways in the last decade. After nearly 30 years of slow and steady growth in total Antarctic sea ice, record low extents were reached in 2017, 2022, and 2023. In 2023 alone, Antarctic sea ice has been well below average for nearly the entire year, continuously setting records since its minimum in February, and advancing much slower than normal during the austral autumn and winter. While the current events appear extreme in the satellite observations, these records only reliably extend back until around 1979, making it challenging to truly understand the historical significance of these recent events. This talk will analyze these events, including the change from maximum in 2014 to minimum in 2017, and the 2022 and 2023 record lows, in the context of monthly and seasonally resolved Antarctic sea ice (both extent and concentration) reconstructions starting in the early 20th century. The large reconstruction ensembles enable a much wider understanding of the significance of these recent extremes in a much larger sample, better helping to determine if Antarctic sea ice is entering a new regime that it has not seen in the last 120 years. Impressively, the reconstructions indicate that recent changes are exceptional even in the context of over a million possible Antarctic sea ice states since the 20th century.